18 year for marriage and 16 year for sex, How justified is all this?

New proposed rape bill of Indian government is saying that people above 16 years of age can do sex on consent of each other. However, biggest issue here is that 18 years is age decided by government of India for marriage. Many people believe that this decision of government will encourage sex before marriage and it is against present social system of India. In Indian culture, sex before marriage is still prohibited where parents do not want their kids to have sex before marriage. 

Now if government passes this law then it will give freedom to kids above 16 years of age to have sex without any fear of punishment. Already many parents have raised their voice against this law because they believe that this law will spoil their children. Overall, this is a very complex question and no one has exact answer to this question. However, one thing is very clear that this law is likely to attract many protests in near future.