I don’t think the Olivia theory holds. Gray shows no evidence of having a spouse, nor does he show any sign of taking his brothers’ pregnancy machine idea seriously. Also, Olivia’s irises don’t have the same shade as normal australium glow (the glow of which is closer to plain yellow than gold, even in the comic she first appears in). We also never see her gold irises ever again after that one panel, which you’d think they’d show more if it were going to lead to something. Chances are, at most, she’s adopted.