We are always busiest during the run-up to Spring Festival. It is the peak time for paternity tests.
Mothers are generally reluctant to come. When a mother turns up, she is often a single mother who wants to get evidence to find out the biological father of the child so she can demand compensation.
They (the migrant workers) are separated from their spouses for a large part of the year. They don't earn much, but they choose to spend a lot on the test. It is such a pity.