Why filial sons can not eat lard

For the deceased parents to do funeral, filial sons can not eat meat, can not eat lard fried vegetables, can not and look at the death of sitting night people to the funeral banquet, to set up another meal in their own stove house, can not eat rice cauldron rice, to eat pots and pans of cooked rice, eat vegetables fried in oil, drink oil tea soup played in oil, the parents died to do the funeral of the filial sons to eat a very light, if you ate the meat that was to eat the parents body meat, prove that they did not fulfill their filial duty, do things against their conscience, is also disrespectful to the deceased parents Meat, proving that they did not fulfill their filial piety, do their own against their conscience, but also to the deceased parents of disrespect.