Monday, May 10, 2010

John Tay on the Scientific Evidence for Homosexuality

John Tay was the Professor and Head of Department of Paediatrics, National University of Singapore (1973-1995) and Head of the Division of Human Genetics in Singapore. He has two earned doctorates based on research in genetics from the National University of Singapore. In this 2010 book, Tay set out to look at the scientific evidence for homosexuality by reviewing all important papers on the roles of genes and environment on homosexuality published from 1991-2009. In his analysis of 50 selected papers, he infers,

The role of genes is far less important than the role of the environmental factors. No properly qualified geneticist will ever say or agree with the statement, "I am born Gay, and I cannot change." Indeed, no form of human behaviour is ever solely inherited. Gene produces proteins and not behaviour. Behaviour is much more complex than a single protein.

For a condition or trait to be inherited, without any influence of the environment, the heritability mus be 100%, for instance, colour blindness. The heritability of the human intelligence is about 75%, whereas the heritability of male homosexuality is only 26% (in the key paper based on the Australian Twin Registry, page xxvi in the [his] book; this figure of 26% was not even statistically significant).

This is a significant book written by a geneticist with impeccable reputation and scientific knowledge. This book is easy to read and does not have many technical terms. I strongly recommend all church leaders and lay members to read this book.


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Blogger Maria said...

Thanks for the helpful review of John Tay's book, Dr Tang. I will definitely look out for this book.

2:10 PM  
Blogger xenobiologista said...

Hi, was directed to your blog by a friend on Facebook. I think the use of the word "heritability" is a bit confusing in this context. As far as I know from what I've read on genetics and mental traits, it's actually heritability of the VARIABLE portion of a trait that is measured, not the heritability of the absolute quantity of that trait.

Having not read this book I can't comment but an important point needs to be made. Just because a trait is not inherited from the parents doesn't mean it's not biological or innate. Over the last several decades, biologists have become more aware of the huge impact that conditions during pregnancy have on the fetus. For instance, people whose mothers were malnourished during pregnancy tend to become fat if they have sufficient food later on because their metabolism is overcompensating, even though this is not inherited genetically. In the case of human sexual orientation, the effect of hormones on the fetal brain is thought to be important.

11:07 PM  

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