The Office of Fair Trading has sent the proposed takeover of Friends Reunited by DC Thomson to the Competition Commission.
Dennis the Menace's publisher was to pay £25m for the websites. But it is not Friends Reunited's tiny slice of the social networking pie that worries regulators.
As part of the deal, DC Thomson subsidiary Brightsolid gets control of genealogy site Genes Reunited. The company already runs other genealogy sites including FindMyPast.com and the 1911 census.
The online genealogy and family history market is huge, and the OFT is worried that the deal gives Brightsolid too large a share of it.
The OFT said its investigation found all the merging firms currently compete with market leader Ancestry.com.
Amelia Fletcher, the OFT's Senior Director of Mergers, said: "People's growing interest in researching their family tree has made this an increasingly important market.
"The proposed acquisition would see the three main providers of online genealogy services reduced to two, and we are concerned this could lead to a reduction in choice or service for consumers. We are therefore referring the merger to the Competition Commission for a fuller inquiry."
The Competition Commission should report back by 16 April 2010.
Friends Reunited was one of the poster children for bubble 1.0. It ticked all the boxes for the mainstream media having been started by a couple in their spare bedroom in 2000 and adding members very fast before selling out to big media. But tbhe company struggled with various business models and interest faded almost as fast it grew. The site lost its way to other sites like Bebo, MySpace and much later Facebook. ®