The current process to identify crime suspect such as DNA profiling or genetic fingerprinting is proven to be almost perfect to convict the guilty and free the innocent. It only has one limitation, if it involves twins. The DNA for two closely related people is more similar than the DNA between two random people which are not related as the probability of two random people in a region is one in a billion whereas for two full siblings, the probability drops to one in 10,000 whereas for identical twins, they have the same DNA profile.
This presents an issue if the potential suspect is one of the twin as there is some ethical issue whereby it is better to let ten guilty man free rather than to imprison one innocent man. Therefore what is the best way to solve this issue?
One of the cheaper and quicker techniques is to apply the concept of DNA methylation. This is basically the molecular mechanism that turn on or off particular genes. The way can be applied to identify which one of the twins is the crime suspect because the two twins might be living in different environment or doing different things which causing their genes to be slightly different. For example, one of the twins might like outdoor activities while the other twins might prefer to stay indoors. However, this technique also having one limitation if the twins are in a very young age or raised in similar environments which the differences cannot be seen.