Devshirme was very popular in the Ottoman Empire. For those of you who don't know (aka: Most of you) devshirme was the practice by which the Ottoman Empire forcefully took boys from Christian families and then converted them to Islam.
The primary goal was selecting and training the ablest children for leadership positions, either in the military or as high administrators to serve the Empire.
The ideal age to recruit (or rather, kidnap) was between 10 to 20 years of age, although much younger boys were taken as well. As you can gather, many parents were not thrilled with the idea of their sons being stolen from them, so they resorted to resisting devshirme and in some cases disfiguring their sons so that they wouldn't be desirable.
While these boys were given power and prestige in their adult life, they were still considered slaves to those who "conquered them." They lawfully owed their selves, their goods, their wives, and their own children to whoever "owned" them, their kidnappers.