Does that include the infertile?
Does it include those who chose not to have children because they didn't want to pass on various illnesses, including mental ill health?
Childless adults are already disadvantaged by the system we have. They pay just as much into the system as parents but get very little back. Childless working adults heavily subsidise single parents working part time on top up benefits. Probably not a popular fact to point out on mumsnet 😂
If anything, childless adults should pay less tax.