I know a married couple who are of 2 different ethinthicies. They took DNA test and she has none of the DNA markers that he has.
Modern science is quite conceited; often rejecting the wisdom of the past because it's "not scientifically proven"; only to later discover it really was true all along.
There is a lot we don't understand about Telegony yet. But the belief didn't come up out of nowhere and was particularly popular among animal breeders (so not caused by factors like interpersonal sexual hangups).
The one bit of recent science I'm aware of (not mentioned on wikipedia) had to do with fetal DNA circulating in her blood. But likely there is more to it. We are only just starting to understand how DNA works. Until just a year or two ago we still thought most the information encoded in DNA was junk. It wasn't, we just didn't understand it. So too are we just coming to understand epigenetics and the non-DNA information that semen conveys to the offspring.
Telegony is a discredited genetic phenomenon that a previous male may influence the characteristics of offspring subsequently borne by the same female to another male. Although its reality was acknowledged by such authorities as Charles Darwin and Herbert Spencer, it has been met with skepticism because of a lack of understanding of the theoretical basis for telegony. With the discovery of fetal genes in mother's blood, the penetration of somatic cells by sperm, and the ability of RNA to program genome rearrangement, mechanisms might exist for telegony.
There are other vectors as well they don't mention as well. For example, humans have more bacterial cells than human cells. Technically, we are a bacterial-human symbiote. 'You' are a whole lot more than just your human DNA. The more you kiss and sex up your wife the more you two swap that non-human DNA. This isn't pie in the sky theory, for example changing your gut bacteria can be used to cause/reverse obesity.
In support of Telegony I offer my own anecdotal observations. I have noticed that couples as they age tend to look more and more alike; to the point of looking like opposite sex version of each other. I have also noticed that women who sleep around tend to change in looks and take on looks common to that type; as if the vast random DNA inputs wrecks havoc on their DNA.
Aside from this coming up recently, what does this have to do with Christianity?
1. Don't worship science. It is continually changing, prone to bias and corruption and gets it wrong more often than not.
2. There will be many things we may not understand about the Bible, that modern culture or science rejects, but which are true nonetheless; even if we don't understand why.
3. This possibly helps illuminate why God found it so important that a woman be a virgin at marriage. (Deuteronomy 22:21). The OT was very big on purity; and telegony contaminates the purity of a man's children. However, while the existence of telephony is far from establish; the negative affects of prior sexual partners on her ability to stay in the marriage is (see here and here).