Two of Tonga's royal cousins are getting married, prompting debate on whether the gene pool is becoming too narrow.
Two great-grandchildren of the late Queen Salote will wed on May 5.
Second-in-line to the throne, 27-year-old Siaosi Manumataongo 'Alaivahamama'o 'Aho'eitu Konstantin Tuku'aho - and now referred to as Prince 'Ulukalala - will marry 25-year-old Sinaitakala Fakafanua, a lesser member of the royal family.
"They want to keep the royal blood to their own family," veteran pro-democracy politician 'Akilisi Pohiva says.
"They are too close. I do not know about biological effects of two close bloods mixed together, but I think they need new blood from outside."
Tongan royal marriages are always arranged, with love only a part of it, and have to be approved by the monarch, King George Tupou IV. Successive monarchs have tried to keep marriages within the family, but that has proved difficult, with there being only nine marriageable women and seven single men - now reduced by one on either side.
They are all great-grandchildren of Salote (1900-1965). In 1969, a 21-year-old princess at Auckland University married a commoner policeman. When word got back to Nuku'alofa, she was hauled home, the marriage annulled and she was married off to a noble.
Of more concern than cousins marrying is the potential cost.
Pohiva, a parliamentary veteran of 25 years, is a member of an investigation committee trying to find out what happened to a $54 million loan a previous government took from China to pay for rebuilding Nuku'alofa after riots in 2006. There are concerns that Tonga is on the verge of default, unable to repay any of its international loans.
Previous royal weddings have been lavish affairs, with the state paying most of the cost.
"In the past, government and the members of the royal family spent huge amounts of money for wedding ceremonies," Pohiva says. "I am sure the coming wedding is going to be a big ceremony. In terms of cost, Tonga's economy is so bad that it is going down the drain."
He said the royal family has a large amount of money invested overseas and should pay for the wedding from its own funds.
"We have males and females from not so different extended families. Whether we call it two families or one family, the main thing is the cost of the wedding."
In the past five years, New Zealand has provided almost $41m in aid to Tonga.
Although the couple are cousins, the marriage is legal and would be legal in New Zealand.
The new bride will have a good chance of becoming a queen. The current king will turn 64 the day before the wedding. A bachelor with no legal heir, he has recently been treated for cancer.
The heir presumptive is the bridegroom's 52-year-old father and king's younger brother, 'Aho'eitu Tuku'aho. As a royal-appointed prime minister from 2000 to 2006, he was deeply unpopular and was eventually forced out of office.
'Ulukalala is ahead of his elder sister in succession, as the royal family favours male heirs.