Someone in your family is sick, and to expose others to whatever you have is bad.
Having too many people in the Church at one time would be unsafe for the general public, and our entire society is adhering to limits on the size of gatherings. Because of this, we have a rotation of who can come each weekend. It is far from ideal, but we are doing our best to make it fair.
Someone in a your household is considered “vulnerable,” and your family chooses not to expose them to the greater risk involved in going out. In such a case, they would be physically able to attend, but the risk to their life constitutes “moral impossibility,” and you need not attend Mass until the danger subsides.