It's not meant to be taken seriously, and meant honestly for amusement. So please, don't comment like you're commenting on a real FMA theory. Just...think and imagine for a little while.
If the theory about Alter!Envy is true, then it's plausible that an Alter!Gluttony exists. We can only imagine what he would look like or what nationality he would be. Maybe, just maybe, he had a son, which may just be the Major we see from Hellsing.
Major never talks about his parents. He fought in WWII for the German army and was promoted time after time until he became..well..Major. He's interested in the supernatural and in Hellsing, we see he has an army of werewolves to send upon London. In manga vol. 5, he even sends about 4 Zeppelins onto London (though they don't call them that, they call them "airships"). Maybe the Major thinks about what happened during the time Ed first walks through the gate? Maybe.
Both Gluttony and Major are somewhat..hardheaded, and both will do whatever it takes to achieve a goal. (Gluttony's goal: eating, Major's:....causing war.) It may just be possible.
An image of Major:
short, fat, and stubby legs (though they aren't there)
Again, please remember that this theory is for AMUSEMENT purposes only. It's not to be taken seriously.