Analysis:
To determine the possibility of the couple having a girl next time, we need to consider the gender distribution of their existing children. Since the question states that the couple has six daughters, we can assume that they have only had daughters so far.

Explanation:
- The gender of a child is determined by the chromosomes inherited from both parents. The father contributes either an X or a Y chromosome, while the mother contributes an X chromosome. If the child receives an X chromosome from both parents, they will be female (XX), and if they receive a Y chromosome from the father and an X chromosome from the mother, they will be male (XY).
- Each child's gender is independent of the gender of their siblings. This means that the probability of having a girl or a boy is always 50% for each pregnancy, regardless of the gender of the previous children.
- In the given scenario, the couple has already had six daughters, which means they have had six pregnancies resulting in girls. The previous pregnancies do not affect the probability of having a girl or a boy in the next pregnancy.
- Therefore, the possibility of the couple having a girl next time is still 50%, just like any other pregnancy.

Conclusion:
The possibility of the couple having a girl next time is 50%. The previous pregnancies resulting in girls do not affect the probability of the gender of the next child.