The reason for that is simple. It's because, often, sick leave is taken in support of dependent children, and that happens with quite frequent regularity. There's nothing particularly wrong with it, but when an employer is looking at two candidates and one candidate for a new job has no children and one candidate has a number of children, that employer is going to be thinking in their head, "What is the risk to my business and to the productivity of my business, the profitability, to the competitiveness of my business if I take the candidate with multiple children versus the one that doesn't?" —that assumes, of course, that those are candidates of the same background, the same experience, the same talent, and the same ability to do the job.