Normally, being a twin means you have someone with almost exactly, or exactly the same DNA as you. For one pair of twins in Vietnam, not only are they not identical, but they don’t even have the same dad.

According to the Mirror, a woman slept with two men during the same ovulation cycle and became pregnant with twins. After giving birth, the man who presumed he was the father of both children was urged by family members to get DNA tests done because one baby had “strikingly different” appearances.

It turns out each baby had a different father. The site reports this is possible if two eggs from the same woman were fertilized by the sperm of two men during the same ovulation period. The details of this particular are unclear, but as of now, they’re reportedly trying to figure out the best way to deal with the very unusual situation.

Source: Mirror