Birthmarks and physical handicaps can result from a possible traumatic and violent death that the native is likely to be deeply affected and may begin a new life with a similar wound or mark.
The abuse of any human organ in the present life may result in either the weakening or malformation (deformity) of that organ in a future incarnation. Likewise, the abuse of any physical organ in the past life will result in deformation or simply issues with that organ in the present life.
Hence positive thoughts and efforts can help to fix conflicting forces behind bodily abnormalities.
Deformed or missing limbs or features may indicate what we did to another in a previous lifetime. Nevertheless, it is essential to note that such events were frequent in ancient times, and probably most of us have committed this type of crime. Other times the incarnating soul may decide to take on this type of anomalies at a sacrifice to work out family karma.