Throughout every part of Edmunds’s life, Edmund is treated as either a monster, an outcast, or a joke by his father. His father views him as not a legitimate son and instead as a burden or consequence of a mistake. Gloucester’s feelings toward Edmund are immediately shown in the first scene of the play.

But I have, sir, a son by order of law, some year

elder than this, who yet is no dearer in my account:

though this knave came something saucily into the

world before he was sent for, yet was his mother

fair; there was good sport at his making, and the

whoreson must be acknowledged. 

(Act 1, Scene 1, Line 19-24)

The unacceptance is very public to the point where his father shows no shame in expressing it. This cuts off any sort of fuel for Edmund to want to receive any acceptance from Gloucester. Edmund, however, is human and all humans have a need to receive acceptance from others. This causes Edmund to pursue acceptance from the citizens of the land that his father controls. This is very much expressed in the famous monologue.

Well, then,

Legitimate Edgar, I must have your land:

Our father’s love is to the bastard Edmund

As to the legitimate: fine word,–legitimate!

Well, my legitimate, if this letter speed,

And my invention thrive, Edmund the base

Shall top the legitimate. I grow; I prosper:

Now, gods, stand up for bastards!

(Act 1, Scene 2, Line 15-22)

He does in the end receive this acceptance which is absolutely great for him, but it does not replace the acceptance that he would have received from his father. Nothing is equivalent to the love of a parent and when Edmund doesn’t receive that love and acceptance, he begins on a neverending quest to receive it from as many people outside of his family as possible. This leads to him pursuing both Reagan and Goneril. This quest for acceptance leads to his downfall as he is later found by the people who would not accept him whom he betrayed.