This raises a question: Frederick I (1152-1190) and Henry II (1154-1189) were contemporaries. Each ruled a huge "empire", had several sons, enfieffed them early, but effectively retained control of said fiefs. Frederick's sons were loyal and waited for him to knight & declare them of age. Henry's, on the other hand, clamored for power immediately after being titled, fought each other, revolted against their father, and even allied with his deadliest enemy, the King of France.
If you compare son-for-son (1066-1250) between HRE & Norman/Angevin England, the German sons were always loyal to the family with a few notorious exceptions (Henries V & VII). The Anglo-Normans, however, regularly hated and rebelled against their father, attacked their brothers, and generally squabbled tooth-and-nail over every inch of their dad's realm.
Was it because the Anglo-Normans beat their kids on a regular basis? Henries I & II were known for their thundering "Norman tempers". I know there were other factors with Henry II's kids (Eleanor), but generally-speaking, does anybody know anything about father-son relations during this period?