II) Concept of Gene

Genes are at least partly responsible for their own survival in future because their survival depends on efficiency of bodies in which they live. Once natural selection consisted of survival of different replicators, now natural selection favors replicators good at building survival machine genes good at controlling embryonic development. A gene defined as any portion of chromosomal material that potentially lasts for enough generations to serve as a unit of natural selection. Replicator is something with high copying and fidelity.
Plans for building human body is divided in 46 volumes- more accurately saying 23 pairs of volume. Filled in every cell is two alternative sets of 23 volume plans (1A, 1B, 2A,.....23B). They are said to be paired because among many pages, page 6 of volume 13A and page 6 of volume 13B might be both about eye color- one might say blue and another might say brown. For such contradictory recommendations, answer varies in which the more dominant gene- here the brown eye color gets expressed with higher benefits for the body and instruction for the recessive character would be ignored though this does not stop them from being passed on to future generations.
Some genes acts as master gene controlling operation of cluster of other genes.

Any one individual body is temporary vehicle for short lived combination for genes. Any one individual may be short lived but gene themselves are long living. One gene may be regarded as a unit that survives through large number of successive individuals. Genes are just the certain length of chromosomal segment, and shorter genetic unit tend to live longer in generations and likely to get split by crossing over. You might have this short length of 8A chromosomal gene that might have been assembled in much more distant ancestor.
As cistrons( a genetic unit)  leave one body and enter next, as they board sperm or egg for journey to next generations they are likely to find that their little vessel contains their close neighbors of previous voyage, old shipmates with whom they sailed on long odyssey from bodies of distant ancestors.
Smaller bit of chromosome tend to have higher chance of passage to future generation. Bigger lump might get lost during the process of crossing over. Hence its slightly less selfish big bit of chromosome and even more selfish little bit of chromosome.
Your children is only half of you, grand children quarter of you in few generations down, most of what you can hope is large descendants, each whom bears only tiny portion of you.
Its just like the hands of cards shuffled. But cards themselves survive the shuffling, genes are not destroyed bu the crossing over they are just shuffled.
( Reference: The selfish gene)