Honestly his nickname is the biggest hint and the joke maybe true. But his mother does consider herself his guardian because she did appear after his incident with Alec
Okay why could the Mad Father song Alive work really well for Stitches through his life. The first verse is a young Stitches who showed homicidal tendencies but nothing worrying. The second verse is when depression and insanity mix. The third verse is him when he still lived in the mansion and the fourth and final verse is Stitches in the asylum.