Tim Sullivan is stepping aside as president of Lehi-based Ancestry.com on Oct. 1 after 12 years of leading the family history company that has seen tremendous growth with the popularity of its DNA tests.

Sullivan will become chairman of Ancestry.com’s board on Oct. 1, a company news release said Tuesday. Howard Hochhauser, the company’s chief financial officer since 2009 and its chief operating officer for the past three years, will serve as interim CEO until a permanent replacement is selected.

“The last 12 years at Ancestry has been a joy for me,” Sullivan said in the release, “but I believe it’s the perfect time to find the right person to lead the company going forward.”

He said the company is well positioned, with a solid management team and a strategic roadmap in place. Revenues for 2017 are projected to exceed $1 billion. Company finances also are in good shape, Sullivan added, citing subscriber growth reaching a four-year high, 40 percent revenue growth in the year’s second quarter and a full-year forecast of 30 percent growth.

Ancestry.com employs 1,600 people, and has a second office in San Francisco, to handle the growing business. More than 5 million people have taken the AncestryDNA test, the release said, helping company revenues grow during Sullivan’s tenure from $140 million a year to more than $1 billion.

“As board chair, I look forward to staying actively engaged with the company and supportive of the management team as they execute our long-range plans,” he pledged.

Sullivan joined Ancestry.com in September 2005 after spending four years in management at Match.com. Before that, he worked for Ticketmaster Online-Citysearch, Inc. and The Walt Disney Co.