How can someone be so ridiculously gullible in a relationship?

I was just reading a FB post about a colored couple holding their white, blonde haired baby. The baby is 7 months old. Baby looks nothing like them.

She claimed their baby boy is the reencarnation of her deceased (died several years ago) best, male friend. The friend had those same features. Supposedly she asked god for her friend to return and her wish was granted when their son was born. And the boyfriend believes in that BS.

There are only two explanation;

1) She cheated with a white, blonde haired man, she's a recessive gene carrier and the poor boyfriend needs to do a paternity test immediately.

2) It is the boyfriend's child afterall and both parents are recessive gene carriers, making the baby look different than both.

But to believe it was god's will and that's her reencarnated male friend is pathetic.

Updates
8 mo
Actually there is one last explanation (unlikely but still possible); that's not their baby. He got switched.
How can someone be so ridiculously gullible in a relationship?
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