He only donated his sperm in 1995. I guess it was used later and that is why the wife thinks he cheated on her.

Sperm can live pretty much indefinitely when frozen. So there’s still a chance the child was born during the years they were together.

Because the offspring of donor parents have the right to contact the person who donated their sperm... The ‘child’ might want to know where they came from, whether there are any siblings, or maybe just to say thank you for providing their mother/co-father the opportunity to have a child. Open mindedness isn’t your strong suit.

Many sperm banks give the children a chance to contact the donor when they're 18

While we don't know where the OP is from, I am going to assume the US, since this is where I am from lol. In regards to sperm bank donations, the donors are almost always anonymous and sign contracts giving up all parental rights and also sign confidentiality contracts. Specific states do allow the child to learn the identity of the donor parent when they turn 18 or 21, depending on the state. However, learning the identity of the parent doesn't automatically give the child the right to contact the parent and turn their life upside down. I can see if the child wanted to know about health factors or something like that, but other than that, no. In addition, OP has no obligation to the child, since their donation was to a sperm bank, rather than an agreement with the mother.

I do not think they have "the right" to invade the donor's life like that. It is extremely selfish, unnecessary and imo it violates the donors privacy and anonymity. The sperm bank probably had all the medical data they needed. And as it was already stated, he has ZERO obligations to the child, he donated some sperm. If anything the child should feel some consequences of his/her actions. Not to mention situations like this might put off people from donating if their privacy won't be respected.

So basically your logic is ‘fuck the kid because the man who jacked off into a cup for some quick cash is more important than someone trying to figure out their ancestral roots, if they have potential illnesses in their family tree, or if they are interested in their paternal background or family roots at all, or another human being trying to discover part of their identity and important medical information’? You’re not ignorant at all.

The child may want to know genetic conditions etc that they would not be made aware about or let alone know who their sperm donor is.

They do medical checks before you can donate. His/her curiosity about "ancestors" does not give him/her the right to invade someone's privacy. All medical information could be obtained without bothering OP. Just because he/she came from his sperm does not make him/her his family. The child has parents who raised him/her. THEY are his/her family.

Besides, I do not understand what is ignorant in thinking anonymous donation should be just that - anonymous and not "anonymous untill potential child decides otherwise".

The donation may not have been used until much later.

Some countries have passed laws removing that anonymity, and giving children the right to know who their genetic father was.