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Old 02-03-18, 03:25 PM
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Re: Genetics of ADHD presentation?

Genes can be turned on and off and regulated throughout life. The underlying genes don't generally change, though. (With rare exception for mutations.)

Think about it this way -- the level of hair on some people's heads changes dramatically throughout life. "Male-pattern" baldness may be inherited through genes -- which don't change, even though the level of head hair does. There are other factors (like age, testosterone level, etc.) that affect the expression of the genes in question.

Similarly, think about menstruation. This is inherited genetically through possession of two X chromosomes, with accompanying development (usually!) of ovaries and uteruses, etc. But little girls with ovaries and uteruses usually don't menstruate -- even though they have the genes and organs to do so. The age at which people begin to menstruate, stop menstruating, how heavily they menstruate, etc. -- those vary, too. These processes are initiated by a complex set of changes to hormone production, etc., during puberty and throughout adulthood -- even if they were originally made possible by inheritance of two X chromosomes.

Some of these X- and Y-chromosome related changes are very dramatic, and others more subtle.

There are other genetic conditions (like Huntington's Disease) -- not related to sex chromosomes -- that usually don't show up until adulthood.

So it's clear that the presentation of many genetically-inherited conditions can change through the lifespan, even if the underlying genes do not.

Similarly, the presentation of ADHD could change throughout life (due to other factors, including hormones, age, environment, etc.) even if ADHD is partly caused by genetic factors that don't change throughout life.
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