I always got the impression that Philip had no relatives left in the USSR. Given that they were supposed to have been born in the 40's, it's not impossible that his parents died during the war.
I think it was fairly common to recruit young men (and probably also women) from orphanages, because they would be much easier to manipulate into good little soldiers. Although, Philip having grown up in an orphanage slightly contradicts his happy (?) memory of having played swords with icicles as a child. I don't know, he has never mentioned his parents and we've only seen him in flashbacks as a young man with Irina. His background is possibly darker and more lonely than Elizabeth's.
Philip in the USSR
I think it was fairly common to recruit young men (and probably also women) from orphanages, because they would be much easier to manipulate into good little soldiers. Although, Philip having grown up in an orphanage slightly contradicts his happy (?) memory of having played swords with icicles as a child. I don't know, he has never mentioned his parents and we've only seen him in flashbacks as a young man with Irina. His background is possibly darker and more lonely than Elizabeth's.