Untitled: The Biological basis of Homosexuality

Gayatrie Pathak By Gayatrie Pathak, 24th Nov 2012 | Follow this author | RSS Feed | Short URL http://nut.bz/k99btjgr/
Posted in Wikinut>Family>Relationships

Opinions on homosexuality span a wide range, and the very mention of the word evokes strong emotional or religious responses from some people. We agree with many others that homosexuality is not a perversion, illness, or sin, but a natural human variation growing out of complex developmental processes that can lead to loving and durable relationships.

The Bilogical side

Opinions on homosexuality span a wide range, and the very mention of the word evokes strong emotional or religious responses from some people. We agree with many others that homosexuality is not a perversion, illness, or sin, but a natural human variation growing out of complex developmental processes that can lead to loving and durable relationships. It was not until 1980, however, that the American Psychiatric Association decided that homosexuality is not a disease and removed it from the Diagnostic and Statistical Manual of Mental Disorders. Interestingly, persons who see homosexuality as a 'mater of choice' (beliefsi.e., having a largely environmental basis) often have a more negative attitude toward gays and lesbians than those who believe that homosexuals are 'born that way', (i.e., have a biological basis). For this reason, the gay community favors a biological interpretation involving hormone chemistry, brain structure, neural circuitry, or genetic factors. their experiences suggest that when others view homosexuality as a fact of life, they are more rational and accepting. The issue of causation is unresolved, however, leading to vigorous debates on scientific inquiry, legal matters, public policy (Friedman and Downey 1994). In any event, the law protects to some degree people with any sexual orientation, even if the private beliefs of others are discriminatory and hurtful.

Maternal genes at work

Several studies of twins have suggested that homosexuality is partly genetic. In pooled data, about 57% of MZ twin brothers of gay men were themselves gay, whereas only about 24% of DZ twin brothers of gay men were gay. similarly, about 50% of MZ twin sisters of lesbian women were themselves lesbian, whereas only about 16% of DZ twin sisters of lesbians were lesbian. Other studies confirm that male homosexuality is clustered in family lines with the brothers, uncles, and male cousins of gay men more frequently gay than in the general population. Virtually all of these male relatives are related to the gay index cases through maternal lines rather than through paternal lines, suggesting that possible genes influencing sexual orientation are on the X chromosome.
X chromosome inheritance of homosexuality has been confirmed by examining DNA marker sites of gay men and their close male relatives (LeVay and Hamer 1994). These sites are polymorphic dinucleotide repeats, VNTRs or RFLPs spaced along the X chromosome within band Xq28, near the tip of the chromosome. A total of 33 out of 40 pairs of gay brothers had exactly the same alleles of five nearby DNA markers, suggesting that this region also contains one or more genes (currently unidentified) leading to homosexuality. This region of the X has about 4 million base pairs, enough for hundreds of genes (among which the loci for hemophilia A and the two X-linked color vision abnormalities). Of course, the fact that 7 pairs of gay brothers were not concordant in this region means that other genes or environmental influences are at work. More recent studies by the same team of investigators (Angier 1995) have extended these observations, showing, for example, that the heterosexual brothers of gay men tend to possess the same Xq28 sequences. Confidence in the idea that a gene influencing sexual orientation resides near the tip of the long arm of the X chromosome should however, wait until other groups of researchers confirm the result.

Natural selection, Mutation, nobody really knows !

A genetic explanation leaves unresolved another issue. Since homosexuality clearly reduces the number of offspring left by gay and lesbian people, why are these characteristics so frequent (2% more or less) in the general population ? One would expect natural selection to reduce the frequency of homosexuality more and more every generation. Explanation that involve increased advantage to the near heterosexual relatives of homosexual individuals are convoluted at best. Perhaps new mutations contribute to homosexuality every generation, but nobody really knows.

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Comments

author avatar Kalimadran
29th Nov 2012 (#)

Wow really nobody has responded to this goes to show how the general population is comfortable with there own sexuality let alone someone else's that may be radically different then theirs. Was an informative read. If you like poetry by any chance her is a link to my stuff I'm always looking for feedback. To my page[/link}

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author avatar Kalimadran
29th Nov 2012 (#)

Sorry messed up the link
To my page

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author avatar Gayatrie Pathak
29th Nov 2012 (#)

Thank you so much ! Would definitely visit your page.
And yes, many are ignorant of certain small yet relevant factors.

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