No, they really donāt, they recognize who cares and meets their needs for them. They will recognize any kind caretaker as a parent, but not a biological parent who hasnāt spent any time with them. Ralph was just a funny fat man he had a play date with one afternoon. If Ralph had actually spent any time with him as an infant I might agree there was some hint of recognition but heās had a total of four hours. Ralph is just another random adult to Alex.
They do recognize the voices of their mother, and hopefully their fatherās, because he was around while she was pregnant, since babies hear their voices in the womb. But newborns will quickly bond to whoever starts caring for them. Caretaking, love and nourishment are what babies respond to.
Itās why men can be referred to as fathers or sperm donors, Alex will have strong bonds with Grandpa, his uncles and probably a step-dad, but at best Ralph might be a curiosity for him as a teen for a brief period that will bring deep disappointment and shame.