In The Republic, Socrates famously argues that children should be raised in common, ignorant of their parentage. If you're going to take an ultra-rationalistic approach to raising children, "treat every child as if he/she is your own" is the ideal.
This debate has been going on forever with victories and losses on both sides. Public school is an example of a triumph on the rationalist side. Of course, just because public schools worked out doesn't mean we should "abolish the nuclear family" but it is a good argument for the utility of this long-running debate.