The implication of what you're saying is that there something fundamental about gender, sexuality, outside interests, etc that stops someone being an understanding, empathic manager. That simply isn't true. Someone with any set of life circumstances can be a good manager, just as anyone can be a bad manager even if they have a very similar set of circumstances.

It's management skills that dictate how good someone is at their management job, not whether they've had sex or not.

Even if the manager's "skills" were good, he wouldn't be respected by the working parents. If he somehow hid his age, virginity, and not having a family (obviously difficult in practice), his reports would probably treat him differently.

If a product manager has the skills and ability to do a good job but a team member is refusing to work with them due to their age, marital situation, whether they have children, etc, then the problem isn't the manager. If I was responsible for that team I'd seriously consider removing that team member.

That's a nice sentiment in theory, but hiring is difficult for most companies (everyone wants to work for the usual suspects, after all). You often can't afford to remove skilled employees because they're being petty. Plus, the executives are probably also older and have kids, so they might agree with the team members' viewpoint.

With any life circumstances? Do you really believe that?

There are circumstances that would stop someone who would otherwise be a good product manager doing a great job, but they aren't simple things like how old they are or what gender they are.