But first impressions aren't used to make the decision for whether you should have a baby with someone. They are used as an initial-filter to reduce the number

But first impressions aren't used to make the decision for whether you should have a baby with someone. They are used as an initial-filter to reduce the number of people that one should invest more time in. It's obviously impractical to put the same amount of effort into every potential partner to determine if they're the person you want to spend 20 years with. You need a way to filter from an incredibly large number of potential partners down to a shorter set that you can invest more time in and get to know really well. If there were a lot of people dating for a couple years and then giving into first impressions your point would have more traction for me. But I don't see a way to manage the "top of the dating funnel" without giving into first impressions.