Due to its more sensitive nature, genetic data is considered special category data under UK data protection law and requires further protections and safeguards.
Firms controlling it should consider having additional security measures in place to help secure it, according to the ICO's guidance.
Its investigation - launched along with Canada's privacy commissioner last June - found that 23andMe breached UK data protection law by not having appropriate authentication and verification measures for customers during its login process.
This included not having mandatory multi-factor authentication to allow users logging in to verify themselves through additional means or devices.
The company also did not have secure password requirements or more verification requirements for users trying to download raw genetic data, it added.
Mr Edwards said such failures and delays in resolving them "left people's most sensitive data vulnerable to exploitation and harm".
"Their security systems were inadequate, the warning signs were there, and the company was slow to respond," he said.
The company says it resolved the issues identified during the ICO and the Office of the Privacy Commissioner of Canada (OPC)'s probe by the end of 2024.
Both watchdogs recently called on 23andMe to protect the sensitive personal data of its customers amid its bankruptcy proceedings.
The company was initially set to be sold to biotechnology company Regeneron Pharmaceuticals in a $256m deal.
But 23andMe said on Friday it had agreed to the sale of its assets to TTAM Research Institute - a non-profit biotech organisation led by its co-founder and former chief executive Anne Wojcicki.
It said the purchase of the company for a new price of $305m would come with binding commitments to uphold existing policies and consumer protections, such as letting customers delete their accounts, genetic data and opt out of research.
A bankruptcy court is scheduled to hear the case for its approval on Wednesday.