For a lot of troll ancestors,their emotions throughout their lives can transcend into the traits and personalities their descendants poses

for example

In his earlier years of life,the signless felt a lot of strong faith passion towards social justice among trolls of low and high blood color,which could explain the personality of a certain red sweater,and very trigger happy troll most of us know,but in the signless's final moments...the amount of passion,rage,sorrow,pain,and so on,is a clear root of karkats very...angry and at times,Problematic personality