I eventually hope to have proper reference sheets and art of all of my characters. For now, have some portraits of Andrew and his twin sister!

They're not quite right. The design needs refining. The gist is there, though. Their eyes are a bit too big and too far apart, making them look even younger than they should. Both of the twins are 23, but appear to be around 18-20. Here they look more like uhhhh high school students, and I ASSURE YOU that Michael is not into that :'D He's surprised to find out that Andrew is almost as old as he is, since he's always seen him as significantly younger (closer to Izzy's age), but Andrew IS an adult.
Maria should be a bit more pretty and glamorous looking, but lord knows I can't draw the effects of makeup. Also Andrew's hair is off. His level of curly and unkempt is shockingly hard to get right. It should be taller on top, shorter on the bottom, and a bit looser looking overall.
Also they do have, like. Literally the same face. The only real differences are Maria's lashes, her lips, and her smaller quantity of less defined freckles, but all of those things are due to makeup. Their freckles generally won't be as dark as they are on this sheet— this is a reference, so it's more to mark placement.

Here's a transparent version without the distracting thingamajigs I added.