There is nothing wrong sharing the truth with your children of his birth. I believe hiding this fact means that you are ashamed of this procedure. And you are afraid of opening up to your family or children’s.
They have the rights to know how they come from. And there is nothing to be ashamed of. They should know how much struggle you did to have them. And at the growing stage, you would develop the sense of humanity and awareness about such procedure. That world thinks false of.
That would much help them understand how great such procedure is. And by doing this you could minimize the little negativity from the world. They are magical babies. And are such a blessing for all the infertile persons.