Short answer:
it's complicated and no-one is quite sure yet.
There are a number of competing theories and no-one has a definitively agreed a theory of why people commit crime at all yet.
Longer answer:
Not only do current research studies / statistics suggest humans with testicals commit more crimes than humans without, but they are more likely to be victims too, especially younger men.
To answer the OP question you really need to consider why any humans commit crime at all.
Current theories suggest there are 4 key things we need to understand to answer this (none of which we have definitive answers for yet).
1) Why do societies define some things as crimes and not others
(so for the OP question a key point is are more things made unlawful that a human with testicals is likely to want to do?)
2) What factors - biological, nerological, upbringing, education, homelife, self control etc - make someone commit crime (and possibly make humans with testicals more likely to commit crimes)?
3) What factors about the environment and situation that a human find themselves in - opportunity for crime, exitence or non-existence of guardians in the area, availability of achohol, levels / styles of policing etc etc - (and why do humans with testicles potentially end up in these criminogenic situations more often than those without)
4) Which of these factors, crime definition, person and environment, and the interaction between all 3, is most important?
(4) is currently hotly debated...but it appears that some combination of these factors currently leads to humans with testicles doing the more crime than those without, we just don't fully understand why yet.
(um, yes criminology is a special interest)