To this day, my second-born son asks why I gave him bad info about how to deal with his older brother. The elder was pesky and very active and easily bored, and wanted to play with his little brother (at least some of the time), and I often suggested the younger (who preferred NOT to play as often) just "ignore" him. Never worked, and things escalated until I had to intervene. I feel guilty even though I tried so hard and read everything there was on sibling rivalry back in the old days. Typical advice was to let them work it out. (They were two years apart, and this went on for more than a decade.) They're friendly now, but not best buddies. Too different.