Genetic-testing startups are finding that selling consumers insights on their risk of getting cancer may not be as easy as telling them about their Irish roots. 23andMe Inc. and Ancestry.com LLC have capitalized on the public’s insatiable appetite for discovering their family trees. However, consumers have balked at paying other companies for health analysis of their DNA. Some testing firms are finding it works better when health-care providers are more directly involved. That way patients are better able to understand test results and integrate them into their care. Helix, which launched in 2015 with $100 million from genome-sequencing giant Illumina Inc., had planned to sell tests directly through an “app store’’ for DNA. Instead, it’s now looking to partner with health-care providers. Illumina said on April 25 that it would no longer hold equity or participate on Helix’s board, ending the partnership.