I would find it more likely the hospital fucked up and you got the wrong baby from the icu. As entering/post leaving said hospital there has always been a paper trail. Records they checked in, record of baby born, and birth certificate. Also birth certificates have changed a bit here, so if you look at your original birth certificate the listed parents had social security numbers listed, when you order a replacement they do not. Guessing a lot of people were worried about family matters stealing identities or something. If I didn’t have said birth certificate, I couldn’t get a driver’s license or anything else really, so unless they faked one well enough and changed records in the hospitals, it’s a very low chance I was stolen. Now the number of men who are lied to about being the father is higher than that, and there are some rare cases of having someone else sign a birth certificate that isn’t the biological father. I have known someone who lied to her ex about how long into a pregnancy she was, and had her new partner sign the birth certificate as the father to get legal paternal rights. (Obviously a shit show when the biological father finds out).