"All men" or "all people" is a trope that should be erased from our vocabulary. Most statements making claims (esp. about the motivation) of "all people" are incorrect. Every person has their own opinion, and you simply can't generalize. Unless it's naïve tautological claims like "all people need food to survive".
Actually, you really can generalise - about large, and especially about large homogeneous - populations.
For example - homosexual men are statistically more likely to belong to larger families. Evolutionary biologists believe that this is due to the presence of childless gay men benefiting the children of their siblings,thus genes that at first blush seem to be "for" non reproduction survive in the pool. (Someone should notify the Boy Scouts that they've got it exactly backwards).
What you can't do is generalise about individuals from their group membership (unless that membership is voluntary, and even that is fraught).
