It’s anecdotal but based on 20-30 years observations. Recall reading something about the Y chromosome being more fragile so age and lab work would agree with this. Just knew lots of 40-ish coworkers and buddies with lots of girls and few boys.

Can't speak to age, but there is a well known phenomenon that fighter pilots only have girls.

What data there is backs that up, too.

https://www.upi.com/Archives/1987/12/01/Air-Force-fliers-rea...

Wouldn't surprise me if similar factors, e.g. stress on the body via aging, also impact the Y chrom and lead to more girls.