Yes but any previous gifts from siblings, aunts, uncles, grandparents and children also need to be taken into account in determining the amount of tax free threshold.
Also, there is a small gift exemption of €3k per annum which a child can gift to each parent on an annual basis free of CAT without reducing the tax free threshold.
If the parent's income is modest the child could look at entering into a deed of covenant with the parents and in certain circumstances the payment may be tax deductible for income tax purposes for the child.