I recently looked it up... for a friend... and he graduated from college in 2016, so he's somewhere around 24-25. I had to check because I came across his Instagram and it was a bit of a thirst trap. My... friend... didn't want to feel creeped out. He's also the oldest of the "kid" actors (Sam Straley who plays Lawrence is only 23) and the one with the largest gap in age from his character. Rewatching this episode made his character my favorite of the sons; in nearly every episode he's taking care of one of his younger brothers but the crowbar thing solidified it.
Edit: Found it. December of '93, he's 25.
Yeah, out of all the boys (minus the baby) I feel like he's the one I know the least about aside from those little bits you mentioned. Even in this episode I feel like I know more about Pat than William. Ironic because aside from McCormack and Cudlitz, the two "kid" actors I recognized from the initial commercials were Caleb (he was in a couple eps of one of Ryan Murphy's shows) and this kid (I don't remember his name) from A Christmas Story.