Your Good Health: Why is one ‘intil’ tw gay, the other straight? - Victoria Tim Colonist

Contents:

• SCIENTISTS FD DNA DIFFERENC BETWEEN GAY MEN AND THEIR STRAIGHT TW BROTHERS
• SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY
• THERE IS NO ‘GAY GENE.’ THERE IS NO ‘STRAIGHT GENE.’ SEXUALY IS JT PLEX, STUDY NFIRMS
• YOUR GOOD HEALTH: WHY IS ONE ‘INTIL’ TW GAY, THE OTHER STRAIGHT?
• THE 'GAY GENE' IS A TOTAL MYTH, MASSIVE STUDY CONCLUS
• TWS WERE BORN TO A GAY COUPLE. ONLY ONE CHILD WAS REGNIZED AS A U.S. CIZEN, UNTIL NOW.
• WE MAY KNOW WHY YOUNGER BROTHERS ARE MORE LIKELY TO BE GAY

SCIENTISTS FD DNA DIFFERENC BETWEEN GAY MEN AND THEIR STRAIGHT TW BROTHERS

In fact, scientists recently intified two specific gen that appear to differ between gay and straight men [1]. In s like this, some might argue that perhaps both tws are actually gay, but one jt hasn’t e out yet. In a study where scientists looked at the sexual aroal patterns of intil tws wh different sexuali—specifilly, where one was gay and the other was straight—they found that gay tws monstrated more genal aroal rponse to same-sex imag, whereas straight tws monstrated more aroal rponse to oppose-sex imag [2].

In theory, this means two people uld rry “gay gen, ” but both of them wouldn’t necsarily be gay pendg on certa environmental factors.

012% of the populatn nsists of a gay or bisexual person who happens to have an intil tw [2]. Tw pairs which at least one tw is homosexual were soliced through announcements the gay prs and personal referrals om 1980 to the prent. Two sets ntaed a pair of monozygotic tws nrdant for sexual orientatn wh the third triplet dizygotic and disrdant for homosexual orientatn.

SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY

Fecundy of paternal and maternal non-parental female relativ of homosexual and heterosexual men. Ngun reported that studyg the geic material of 47 pairs of intil male tws, he has intified “epigeic marks” ne areas of the human genome that are strongly lked to male dividuals, said Ngun, the prence of the distct molecular marks n predict homosexualy wh an accuracy of close to 70%. Geicists suggt that together, the human genome and s epigenome reflect the teractn of nature and nurture -- both our fixed herance and our bodi’ flexible rpons to the world -- makg who we ’s study of tws don’t reveal how or when a male tak on the epigenomic marks that distguish him as homosexual.

”To fd the epigenomic markers of male homosexualy, Ngun, a postdoctoral rearcher at UCLA’s Geffen School of Medice, bed through the geic material of 47 sets of intil male tws. Thirty-seven of those tw sets were pairs which one was homosexual and the other was heterosexual.

But the existence of tw pairs which one is homosexual and the other is not offers strong evince that somethg other than DNA alone fluenc sexual orientatn. So they unleashed a mache learng algorhm on the data to search for regulari that distguished the epigenom of homosexual tw-pairs om tws which only one was ne pact regns sttered across the genome, they found patterns of epigenomic differenc that would allow a predictn far more accurate than a random gus of an dividual’s sexual orientatn, Ngun reported Thursday.

THERE IS NO ‘GAY GENE.’ THERE IS NO ‘STRAIGHT GENE.’ SEXUALY IS JT PLEX, STUDY NFIRMS

McCarthy and other experts utned that the disvery of epigenomic marks suggtive of homosexualy is a far cry om fdg the of sexual distctive epigenomic marks observed by Ngun and his lleagu uld rult om some other blogil or liftyle factor mon to homosexual men but unrelated to their sexualy, said Universy of Utah geicist Christopher Gregg. Michael Bailey, who has explored a range of physlogil markers that pot to homosexualy’s origs the womb. But the existence of intil tw pairs which only one is homosexual “nclively suggt that gen don’t expla everythg, ” Bailey Ngun’s rearch needs to be replited larger studi of tws, advanc the fful procs of better unrstandg how — and when — a boy’s sexual orientatn velops, Bailey me on Twter @LATMelissaHealy and “like” Los Angel Tim Science & Health on rarely get ncer, now scientists thk they know whyThree rearchers w Nobel Prize chemistry for studi of DNA repairMars had a long-lastg seri of lak, NASA’s Cursy rover fds.

S., and Sndavia durg the last two s all arrive at the same ncln: gays were not born that way. If homosexualy is ed by geics or prenatal ndns and one tw is gay, the -tw should also be gay.

YOUR GOOD HEALTH: WHY IS ONE ‘INTIL’ TW GAY, THE OTHER STRAIGHT?

“The predomant thgs that create homosexualy one intil tw and not the other have to be post-birth factors.

About half of the homosexual/bisexual populatn ( a non-theraptic environment) mov towards heterosexualy over a lifetime. About 3% of the prent heterosexual populatn once firmly believed themselv to be homosexual or bisexual. Numbers of people who have changed towards exclive heterosexualy are greater than current numbers of bisexuals and homosexuals bed.

THE 'GAY GENE' IS A TOTAL MYTH, MASSIVE STUDY CONCLUS

“The thors were pro-gay and they mented that the only stabily was among the heterosexuals, who stayed the same year after year.

Scientists may have fally solved the puzzle of what mak a person gay, and how is passed om parents to their children.

TWS WERE BORN TO A GAY COUPLE. ONLY ONE CHILD WAS REGNIZED AS A U.S. CIZEN, UNTIL NOW.

A group of scientists suggted Tuday that homosexuals get that tra om their oppose-sex parents: A lbian will almost always get the tra om her father, while a gay man will get the tra om his heredary lk of homosexualy has long been tablished, but scientists knew was not a strictly geic lk, bee there are many pairs of intil tws who have differg sexuali. Scientists om the Natnal Instute for Mathematil and Blogil Synthis say homosexualy seems to have an epigeic, not a geic thought to have some sort of heredary lk, a group of scientists suggted Tuday that homosexualy is lked to epi-marks — extra layers of rmatn that ntrol how certa gen are exprsed. In homosexuals, the epi-marks aren't erased — they're passed om father-to-dghter or mother-to-son, explas William Rice, an evolutnary blogist at the Universy of California Santa Barbara and lead thor of the study.

"There is pellg evince that epi-marks ntribute to both the siary and dissiary of fay members, and n therefore feasibly ntribute to the observed faial herance of homosexualy and s low nrdance between [intil] tws, " Rice and his team created a mathematil mol that explas why homosexualy is passed through epi-marks, not geics.

Evolutnarily speakg, if homosexualy was solely a geic tra, scientists would expect the tra to eventually disappear bee homosexuals wouldn't be expected to reproduce. But bee the epi-marks provi an evolutnary advantage for the parents of homosexuals: They protect fathers of homosexuals om unrexposure to ttosterone and mothers of homosexuals om overexposure to ttosterone while they are gtatn. "The epi-marks protect fathers and mothers om excs or unrexposure to ttosterone — when they rry over to oppose-sex offsprg, n e the masculizatn of femal or the femizatn of mal, " Rice says, which n lead to a child beg gay.

WE MAY KNOW WHY YOUNGER BROTHERS ARE MORE LIKELY TO BE GAY

Rice not that the markers are "highly variable" and that only strong epi-marks will rult a homosexual scientists have long spected some sort of geic lk, Rice says studi attemptg to expla why people are gay have been few and far between. " Homosexual behavr has been observed black swans, pengus, sheep, and other animals, he 's mol still needs to be tted on real-life parent-offsprg pairs, but he says this epigeic lk mak more sense than any other explanatn, and that his team has mapped out a way for other scientists to tt their work. The study of nearly a half ln people clos the door on the bate around the existence of a so-lled “gay gene.

It is worth keepg md that this study only vers some typ of sexualy — gay, lbian and cis-straight — but don’t offer many sights to genr inty. Humans have tried to unrstand human sexualy for centuri — and geics rearchers joed the ay the early 1990s after a seri of studi on tws suggted homosexualy ran fai.