Suppose there is a girl who was born when her mother was sixteen.  And her mother was born when her grandmother was sixteen.  And suppose this burden of caring for a child at the age of 16 has contributed to an intergenerational cycle of poverty that has harmed her family and her education.

A boy of sixteen comes to her and says (roughly translated),

“Hey girl, your mother recklessly had a kid at age 16, and her mom recklessly had a kid at age 16, so you should get with me and recklessly have a kid at age 16!  After all, if they didn’t do the same thing, you wouldn’t exist!”

Is this a good idea?  I mean, after all, if they didn’t do it, she wouldn’t exist.

No, it is not a good idea.  In fact, this argument does not make sense…

unless, implicit in the argument, you have access to a time machine and can change the past.

However, if one did have a time machine, that opens up an entirely different bucket of ethics which this argument completely fails to address.

This applies to abortion regardless of whether other arguments are also valid - “but if your mother aborted you…” implies time travel.

This applies to immigration, regardless of whether other arguments are also valid - “but if immigration laws were different…” implies time travel.