Between having kids and coming out later in life, and/or adoption and/or various other ways, there are lots of gay men with kids - but let's not quibble about that, just different experiences talking I expect. As a gay dad I run into gay dads all the time.
The common belief part was what I was wondering about, do gay men really have more problems with aging than straight men - and why - or is it just a negative stereotype as you mention?
Lots of discussion locally about the need for gay and lesbian retirement homes, the lavender-grey wave. With a much higher percentage of women than men in assisted living and/or care homes, maybe this is more of a gay concern than a lesbian one.