SEOUL, Dec 1 — When news broke that South Korean actor Jung Woo-sung and model Moon Ga-bi had a child together despite not being married, the question on everyone’s mind is: which surname will the child have?

According to The Korea Herald, in South Korea, children usually take their father’s surname, as required by law. However, if the parents agree when they register their marriage, the child can take the mother’s surname instead.

The situation is more complicated for children born outside of marriage.

The Herald quoted lawyer Kim Mi-ru, who explained on a radio programme, that such a child might initially have the mother’s surname. However, once the father officially acknowledges the child as his, the child usually takes his surname.

If the father refuses to acknowledge the child, legal action, including a court case, can be taken to establish the parent-child relationship.

As Jung has already confirmed he is the father of Moon's child, the Herald reported that lawyer Son Su-ho, in a CBS radio interview on Wednesday, explained that the child could have either Moon's or Jung's surname.

“Birth registration can be completed by the mother alone. However, using Jung’s surname is also possible, as Jung has acknowledged that he is the father,” Son was quoted as saying.

He went on to explain that once the father acknowledges the child, the child typically adopts the father’s surname.

However, he added that the parents could either agree to keep the mother’s surname or ask the family court for approval to do so, meaning the surname ultimately depend on the parents’ decision.