Although it may not be palatable for some, did you know it is legal to marry your first cousin in many states in Australia?

"According to the Marriage Act of 1961 [cousins] can marry," Genealogy SA's Beryl Schahinger told ABC Radio Adelaide's Afternoons program.

The Act, last amended on October 21, 2016, states:

23.2 — Marriages of parties within a prohibited relationship are marriages: Between a person and an ancestor or descendant of the person; or Between a brother and sister (whether of the whole blood or the half-blood)

"You can also marry your niece or nephew or your aunt or uncle," Ms Schahinger said.

Love is blind, though genetic complications may follow. ( ABC News: Clarissa Thorpe )

Currently, the Act states marriage is "the union of a man and a woman to the exclusion of all others, voluntarily entered into for life".

The Federal Government announced this week that it would gauge public sentiment on same-sex marriage via a voluntary postal plebiscite.

The Act also states the minimum age for marriage is 18, though a judge may allow one partner to be 16 or older due to "exceptional circumstances".

Ms Schahinger said it was not unusual for removed cousins to learn of their common genetic link during the marriage process.

"A couple of my cousins married, and they only found out at the reception that their grandmothers were sisters."

The genetic minefield marrying cousins face

Although common in centuries gone by, inter-family marriage creates enormous genetic stress, Professor David Thorburn of the Murdoch Children's Research Institute said.

"There is an increased risk of having what is called recessive diseases," Professor Thorburn said.

"All individuals share about 99.5 per cent or more of their genetic material, so there is a small amount that varies between individuals.

"First cousins share about one-eighth of that variable part of the genetic material."

Professor Thorburn said this meant married relatives had a slightly lifted risk of having a child with a congenital or inherited disorder.

Around one-quarter of the variable material is shared between uncles, aunties, nieces and nephews.

"All of us are at around a 3 per cent risk of having a child with congenital anomaly; the risk is roughly double for children of first cousins," the professor said.

"It used to be very common practice in European history for cousins to marry. You only have to look at the royal lineages.

"Once you get past second cousin [removed] marriages, the [disorder] risk is very hard to see," he added.