
Hackers have been able to gain access to personal information from about 6.9 million users of genetic testing company 23andMe, using customers' old passwords.
In some cases this included family trees, birth years and geographic locations, the company said.
After weeks of speculation the firm has put a number on the breach, with more than half of its customers affected.
The stolen data does not include DNA records.
23andMe is a giant of the growing ancestor-tracing industry. It offers genetic testing from DNA, with ancestry breakdown and personalised health insights.
The biotechnology company, which is based in South San Francisco, was not hacked itself but cyber-criminals logged into about 14,000 individual accounts, or 0.1% of customers, by using email and password details previously exposed in other hacks.