I wouldn't aim to justify your lack of experience if an interviewer doesn't directly ask you why. If it comes up, just be honest and explain that you had to handle things at home. Try to twist it a little and explain what you gained from that (strengths gained and weaknesses resolved for example). The main thing that you should be looking at doing in this case is displaying to the interviewer that you don't lack experience due to a lack of drive and motivation, yet due to circumstances outside of your control. And in that respect, you are just as motivated as say, a co-op that already has 2 internships under their belt, or someone with years of experience. A certain someone at Accenture noted that they don't discriminate in the hiring process based on what one has done. Yet base things off what they have gained and interpreted from said experiences. In this respect, something as simple as university group work could suffice provided that you are an optimal applicant. It's more about who you are as opposed to what you've done to a certain extent.
Expect rejections from a fair few places as this is common with everyone, yet don't let your lack of experience discourage you to continue applying. Just go through the interview with the confidence of someone with years of experience.
I'm not too versed in the hiring process as some of the more senior members of the site, but i like to think i know a thing or two.
