The simplest code I could come up with would be:
var hasAny = children.Any(motherString.Contains);
If you expect each of the words to be seperated by a space then you could use this:
var hasAny = motherString.Split(new[] { ' ' }).Any(children.Contains);
If the words in motherString could be seperated by other characters, you could add them like this:
motherString.Split(new[] { ' ', ',', ':' })
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…