How do I tell MY children??????

That I am donor conceived and have two fathers?
That the man I do not know who I am descended from will never be known to them. That they will never know their "grandfather" and other members of his and therefore their family.

It is hard enough explaining to adults that the man I call dad is not my father, but trying to explain it to a 3 year old is another kettle of fish. Now 3 year olds are generally pretty smart and have already worked out a lot of things in the world.
She knows that Mummy's Mummy is Grandma and Mummy's Daddy is Poppa. She also knows that Daddy's Mummy is Nanna, and although we've never said it she knows that the man associated with Nanna who she calls Pa is not Daddy's Daddy. As she has specifically asked me who and where my Daddy is.

First it breaks my heart that the man who raised me passed away when I was 10 and that I cannot take her to meet him. I have not even begun to try and explain life and death yet. All she knows is that the man in the photo is my Daddy. But this will not last long as she is in the period of "why?" in her life - everything is "why?".

She is also very switched on in regards to inheritance. She has the same hair and skin as Daddy but the same eyes as Mummy. It wont take her long before she realises that Daddy does not look anything like the man in the photo and that he also does not have the same hair, skin and eyes as Nanna. She will want answers to questions. Then I will have to try and explain why I have two Daddy's, both of whom she will never be able to know. This will also not fit into her picture of the family unit, after all she sees that all of her friends have one Daddy and one Mummy - so how can her Daddy have two? She wants her grandfather, but I cannot give her one. Sure I can give her the man who raised me through the way he raised me and the values he instilled in me but she has no tangible link to him as they are not biologically related.

My children will not be able to fill out family trees at school or know from which country they are descended from. They will not know what inheritable diseases affect their father's side. Even their name does not match the blood they have.

It is bad enough that this has happened to me but seeing that it already affects my own children breaks my heart even further.