Answer:
The correct answer should be - no doctors or government can not decide if they can have children together or not, it is their personal decision and one can explain complications and consequences only.
Explanation:
Tay-Sachs disease is autosomal recessive disorder it means for the affecting an individual it requires both copy of the affected allele and in heterozygous condition individual act as a carrier and pass the affected gene to next generation. In this case, both parents are heterozygous which means there are 25% chances to have an affected child.
A genetic counselor or doctor can explain the problems parents can have with the affected child and what are the chances of the affected child, however, they can not and should not decide if they both should have children together or not as it is their personal choice and they should be responsible for pro and cons.