Watch size for next generation

[Coroner]

I plan to hand my watches down to my kids when the time is right. With my wrist size, I'm able to wear 40mm-43mm size watches. Now from what I can tell, it looks like my kids will be bigger and taller than I am. So the question is, does a person only buy the biggest possible watch size they are able to wear in order to ensure that the next generation will wear them? It would kill me if the watches were just placed in a safe because the new owners feel the watch is too small. I don't know the specifics, but I know every generations is getting bigger than the previous.

Thanks,
G