What do you think.. Do our genes change from day to day? So your genes does not change from day to day, nor in your lifetime (excluding mutations), but your gene expression can change from day to day...
You will always have the same genes, but which genes that are actually translated will depend on what your environment exposes you to, what stage in development you are in, what other genes are on, and so on. And yes, there are ways to test this, but only in a specific cell type at a time. You can use a gene chip analysis to check what genes are expressed at a given time. This is used in a lot of disease research, like cancer, to see how that disease changes gene expression in a given cell.
