In a recent AMA on Reddit, lead writer on the first two Mass Effect games Drew Karpyshyn expressed surprise at people getting horny for Garrus.
A new Mass Effect is on the way, one that might see the return of the Geth, so anything could happen.
“We always knew they’d come back as companions,” wrote Karpyshyn in the AMA when asked about how Garrus and Tali were brought in as romance options for Mass Effect 2.
“The various species in Mass Effect are too biologically different to breed with each other,” wrote Karpyshyn.