I did not archive back when I read this on this subject a few years back but Maggie visited Castro about 9 months before Justin was born. There is a pic on the internet of that visit and she took his older brother with her and Castro is holding the older son in the pic. I posted it on fb back then but have since scrubbed all my fb posts.
[–] 23478374? 2 points -2 points 0 points (+0|-2) ago
There's no evidence, it's just a funny meme due to them looking very similar.