Hi Sukham,
As diploid organisms, we inherit 2 sets of chromosomes, one set from our father and the other from our mother. Normally, you'd expect these genes to be expressed to the same extent (the differences in the genes would only come from the protein products they make, not the inherent level of transcription and translation).
However, you can have cases where there is a different level of expression between the mother and father. There is full imprinting, where one parental gene can be completely repressed, or partial imprinting, where the paternal and maternal genes are differentially expressed.
This is a form of epigenetic regulation beyond the sequence of DNA.
I hope this helps,
Katt