They are expected to choose based on intellect rather than their emotions. Whether or not they feel empathy, they still know the difference between right and wrong at an intellectual level. Yes, they are at a disadvantage, and this should factor into the kind of punishment they receive. Nevertheless, they are responsible for their actions for even though they knew it was wrong (or at the very least that society considers it wrong and being caught carries certain penalties) they did it anyway.
This is not the only mental illness that puts people at a disadvantage when it comes to committing a crime. A pedophile, for example, is severely disadvantaged when it comes to leading a life free of any sex offenses. It's easy for most of us to refrain from molesting children or viewing child porn because we have no interest in those things. But for a pedophile it is difficult. Through no fault of their own, they were born with a condition that makes them attracted to sexual activities that are not legally permissible. Yet we rightfully expect pedophiles to follow the law or face the consequences despite the fact they are at a disadvantage compared to us.
The same could be said about stealing for those with kleptomania or other compulsive disorders, or of assault and battery for those born with a short temper.
Why even draw the line at biology? There are those born into social settings that put them at risk of committing certain crimes and at a severe disadvantage compared to those of born in more affluent settings (think of those born into a drug dealing household, for example).
There will always be things that put some at a disadvantage. Those things may be biological, sociological, or otherwise. Regardless, society depends on obedience of the law even if you are predisposed to breaking it. In fact, one could argue that the whole purpose of punishment is to give those already predisposed to breaking the law a larger incentive not to. ie. You may not care about people's feelings and don't mind murdering them, but you care about your own freedom, so hopefully the threat of a severe sentence will keep you from murdering.