It's not hard to build pressure cooker bomb. Older brother was studying engineering at some point. I don't doubt he was perfectly capable of making a pressure cooker bomb.
exactly - also worked as an auto mechanic. That was one of the uncle's
gripes about the older brother, called him a loser, said he had skills and could have worked if he had wanted to .... the father is a contractor back in Russia! The mother has worked as a lawyer.
Younger brother has good math skills according to family and fellow students - wanted at one time to be a doctor (surgeon) and is smart and sociable -
So no lack of brains and a few skills between the brothers.
The question I have is 'where' did they build their bombs if they did?