In his account of Œdipus, Hyginus writes:
[Œdipus] fortissimus præter ceteros erat eique per invidiam æquales objiciebant eum subditum esse Polybo, eo quod Polybus tam clemens esset et ille impudens.
My attempt at a literal translation would read something like
[Œdipus] was far stronger than the others, and out of envy his rivals would mock him, [saying] that he had been falsely substituted as Polybus' [son], since Polybus was so mild and he [so] shameless.
Mary Grant's translation in The Fables of Hyginus reads:
[Œdipus] was courageous beyond the rest, and through envy his companions taunted him with not being Polybus’ son, since Polybus was so mild, and he so assertive.
So I see that my translation is more or less correct. But what I don't understand is how eo is working in eo quod Polybus tam clemens esset it ille impudens. Both my translation and Grant's seem to ignore it.
Can anybody enlighten me?