Your Good Health: Why is one ‘identical’ twin gay, the other straight?

Dear Dr. Roach: I read your recent column regarding identical twins where one of the two was balding while his twin was not. Within my extended family, there are identical twin brothers, who also were almost impossible for family members to differentiate. If their DNA genes are “identical,” now that they are adults, how can one be homosexual, while his twin is married with children?

Anon.

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Sexual identity defies a simple, single explanation and even categorization.

As time goes on, scientists have recognized that not everybody fits into the clear-cut categories of “straight” and “gay.”

Some people are attracted to both sexes; some to neither; some feel that traditional gender roles don’t really fit them.

As such, trying to identify a single cause of sexual identity, genetic or environmental, is not going to be successful.

With increasing recognition that people do not fall into binary categories, we can see the limitations of studies that have attempted to answer your question. Nonetheless, the data is useful to look at.

Studies have shown that in identical twins, if one twin is gay (the term “homosexual” is used in clinical studies but is considered offensive, so I won’t use it further), then 30 per cent to 66 per cent of the identical twins also will be gay. As this is much higher than the overall rate in the population, this suggests some, but not absolute, genetic influence.

However, an adopted sibling of a gay person is also more likely to be gay (11 per cent in one study), suggesting that the familial environment also plays a significant role.

My opinion is that there are both genetic and environmental predisposing factors that help determine sexual orientation.

As for the case you are describing, there are many things to consider.

Some people who are attracted to the same gender can be so afraid of, or put off by, the social stigma against same-sex couples that they marry and have children with a person of the opposite sex despite being primarily or uniquely attracted to those of the same gender.

Some people have found that they may be attracted to a person of either gender; their choice of life partner depends more on the partner’s personality and their unique situation than on his or her biological sex.

Sexual identity is not a choice. We cannot choose to whom we will be attracted. I’m afraid many people fundamentally misunderstand this point.

Human beings are wonderfully complex, and I hope you look at the twins in your family not merely with acceptance for who they have chosen to spend their life with, but with appreciation for the diversity that can enrich our lives.

Dear Dr. Roach: Why does drinking one small glass of wine make me spacey and sleepy now that I’m over 55? What physical change has occurred in my body, and should I be concerned about that as regards other functional changes that might not be as obvious?

C.C.

Your ability to metabolize alcohol generally decreases as you get older. This means the same amount of alcohol will have a greater effect, assuming you are the same size you used to be.

The liver is also responsible for getting rid of medications and their metabolic byproducts, so sometimes doses of medicines need to be adjusted for people as they get older (55 is not old, at all, but it is older than age 20).

This effect becomes more prominent in a person’s 70s and 80s. A wise person will adjust their dose of alcohol accordingly.

It is possible, but unlikely, that there has been a functional change in your liver not due to age, so mentioning it to your doctor will allow him or her to consider whether any testing may be necessary.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.
 

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