Now now, its not Kankuro's fault he has to raid the makeup cabinet for his traditional methods of the Puppet Master.
As predicted, Gaara would single handedly have the largest amount of suffering in his childhood. Family or not, his own father wanted him dead at one point.
Its been shown the most of Gaara's suffering, so natural there is overwhelming evidence that Gaara suffered.
Haku though shared a similar life, albeit less shown, when Haku's bloodline were hunted down. Mother killed by Father, Haku trapped and killed him. Haku assimilating into becoming a "weapon".