Yes, ego came into the children of the Gurus (Enlightener). The first Guru's sons weren't very happy because none of them became the second Guru. The first son was especially expecting it to be him, but Bhai Lehna Ji, the first Guru's disciple, became the second Guru. The second Guru's son, Bhai Dattu Ji, was so upset that the third Guru wasn't him. He actually went up and kicked the third Guru, Guru Amar Daas Ji, even though Guru Amar Daas Ji was much older than him. Out of respect for Guru Angad Dev Ji (second Guru), Guru Amar Daas Ji didn't attack this young man back. 

The fifth Guru's elder brother (Baba Prithi Chand Ji) was actually quite upset that the Guruship went to the youngest brother. He expected it to come to him because he was the eldest. However, it didn't go to him, it went to the younger one and he was quite upset. For many years, he would call himself the True Guru. He would steal all the donations from the Sangat (congregation), just for himself. He did this with hopes that his younger brother, Guru Arjan Dev Ji would have a really hard time. Guru Arjan Dev Ji did have a harder time building Harmandir Sahib in Amritsar. This is because there was very little funding coming for it. Most of the money was taken by the elder brother. So ego was inside all the families of the Guru. Ego is just everywhere.

You can watch Bhai Jagraj Singh explain this topic in the video below: