There is an increased risk, but it's a lot lower than most people think. Probably in the vicinity of 7% to 11% increased risk of serious birth defects.
These numbers may very well be high, as they're extrapolated from surveys based on very small sample numbers.
The real reasons for avoiding incest are emotional and societal, not genetic.
So, if, e.g., the risk of being born with a cleft palate is on the average 1 in 700 when the parents are non-consanguine, then incest would boost that risk to only 1 in 650 to 1 in 620?
Regards,