You can meet term "Boyar Sons" in number of Medieval military themed computer games where they depict Russian military "unit". I have always assumed that these are supposed to be literally sons of boyars (boyar = Russian aristocratic title, roughly equivalent to Count or Duke). Just recently I have found out that that's not what that term means.
First of all, Russian original is "deti boyarskie", which means "children of boyars".
Second, term like "father", "brother" and "son/child" when used in Medieval legal writing meant feudal relations, not family relations. If somebody was called "child" of somebody, it meant that he is his vassal. If word "brother" was used, then they were of equal status (two kings for example could call one another "brother", as long as they acknowledged their kingship). Consequently "father" was suzerain.
Therefore "Boyar Sons" means smaller feudal lords serving under boyar.
First of all, Russian original is "deti boyarskie", which means "children of boyars".
Second, term like "father", "brother" and "son/child" when used in Medieval legal writing meant feudal relations, not family relations. If somebody was called "child" of somebody, it meant that he is his vassal. If word "brother" was used, then they were of equal status (two kings for example could call one another "brother", as long as they acknowledged their kingship). Consequently "father" was suzerain.
Therefore "Boyar Sons" means smaller feudal lords serving under boyar.