I think it's important to remember that this study is the first of it's kind to look at the overall volume and shapes of brains within the group. Most notably lesbian women and straight men had asymmetric brains, with the right hemisphere slightly larger than the left. Gay men had symmetrical brains like those of straight women.
Brain volume and shapes are not "learned" traits and formed in the womb.
Secondly, They used scans based on positron emission to measure blood flow to the armygdala: Image below;
The mathing of gay men and strainght women and gay women with straight men might also explain why women are three times more likely to suffer from mood disorders or depression. Gay men have higher rates of depression too but this might be due to thier own biology or having to deal with homophobia.
In straight men and lesbians, the amygdala fed signals mainly to trigger "fight or flight" responses which is more of n action response mechnism in men.
This study shows that homosexuals of both sexes share not only brain volume and shape of thier counterparts but also brain connectivity.
Finally, they have looked at sexual orientation with no direct sexual orientation like past studies.
One more thing, we should be cautious when claiming that the west accepts homosexuality as this is not always true when you consider Iris Robinson (MP Northern Ireland Assembly) talking on BBC Radio:
Homosexuality is disgusting, nauseating, shameful, wicked and vile
She went on to state how her christian belief "told her" homosexuality is "an abomonation" and she advised homosexuals to psychiatric help. Interpretation of religous belief like this should not go unchallenged.