Named after his father (and his father's grandfather), MJ's proud to carry the name Mieczyslaw, but he's also not about to spend his life correcting people on how to pronounce it. Growing up, it was clear that MJ took after his dad in a lot of ways; excitable, easily distracted, always needing to be on the move. When he was 12, they learned that he took after his mom, too; he shifted for the first time, and attacked his dad. Malia was able to stop him before he hurt Stiles too bad, but that night left scars on both of them. 

After that night, MJ became more anxious and started having panic attacks, which often caused him to start turning, which only made him panic more. His parents did their best to help him cope and teach him control. In the end, though, Scott had to help him control the shift as his alpha.