YES They KNOW Even If You Don't Tell Them

A common experience among the children of sperm donors is that they somehow KNOW it even if you don't tell them. Which just shows that they are NOT growing up in an absolutely normal conditions, despite their exterior happiness and adjustedness. They have always felt something was off, and from everything I've read, they are usually not surprised to find out the truth. Here is Plotz reaveling what he found in his own research into what happened once parents told their children the truth:

Their kids were generally not surprised, they report: Some kids told their moms that they always felt something was off.

And:

Gage says he wasn't very surprised when his mom broke the news: "I have always noticed differences between my dad and me. … His personality is nothing like mine." Many mothers said their kids felt "relief" when they learned dad was not dad. As Jacob's mom put it, "He always knew but he didn't know."

Oonce they are told, the children tend to feel the following:

They find themselves with children who no longer know exactly who they are and no longer have a complete family. The mothers don't have much to tell them.

So now, these mothers are interested (finally) in helping their children re-establish their identity and learn about their donor fathers:

Some mothers with a single child hope to find genetic siblings, perhaps to build a new kind of family. And one divorced mother says she dreams about meeting her donor, maybe falling in love, and having him become, at long last, the father to his own children: "Wouldn't that be a story and a half?"

Good luck. That's the kind of thing that's supposed to happen BEFORE you have someone's child!