The evidence is currently ambiguous.
In the scene where the connection is revealed, Otto specifically says,
"This is my father, Andreas von Strucker. My father and his sister Andrea did unspeakable things. They were terrorists. They were also mutants."
This implies that only Andreas is his parent, and Andrea is not.
Now, you could imagine, "He was embarrassed about it and so he was hiding the fact that Andrea was his mother as well." Or maybe "He didn't know his mother was also his aunt."
However, generally speaking, it's easier to be certain of a person's mother rather than their father. If he was born to Andrea von Strucker, he would likely have a birth certificate somewhere and hospital records, and so it would be more logical thing to claim "This was my mother, Andrea von Strucker. My mother and her brother Andreas did unspeakable things."
It is certainly possible that Andrea was his mother and managed to hide her pregnancy and Andreas, for whatever reason, claimed the child as his own, but it requires a lot of supposition that so far isn't supported by any evidence. The very fact that the Strucker kids inherited their abilities from their father (who had children with an unrelated human woman), who inherited it from his father (who presumably didn't have a child with anyone related to him), who inherited it from Andreas, suggests that only one parent is needed to pass on the powers.
It may also be that the elder Strucker siblings had an incestuous relationship but had other partners or relationships as a cover, or for variety, or for periods when they believed it was wrong. But for the first season there was no real evidence that Andrea was Otto's biological mother, other than that a few comics have hinted at that the twins had an abnormally close relationship in comics canon.
In episode 9 of season two, during a confrontation with someone who worked with Reed Strucker's father, she said,
"Reed's grandparents were monsters. They killed thousands of people."
Which suggests that his two grandparents were the Struckers.
However, there are other explanations:
1) It was a slip of the tongue in a tense moment, she meant "Reed's grandfather and his sister."
2) She was referring to Reed's grandfather and presently unnamed grandmother, who, although not Andrea Strucker, was also a monster implicated in the murders of thousands of people. One could easily imagine that, if incest were ruled out, anyone Andreas had a child with might well be at least comfortable with his acts and might also be a mutant.
3) She suspected incest but was simply wrong (given the character is a geneticist and had access to samples of Reed's genetic code, this is least likely but included for completeness).
It is enough evidence that, at present, I can't say "Probably not," (especially considering the comics constant hints in that direction between the Fenris twins) but not quite enough to say it is confirmed. Future episodes may shed more light on the topic.