A common suspicion of past and contemporary people is that they have inherited these practices from their ancestors. About them, Allah the Almighty said:

Just in the same way, whenever We sent a warner (i.e. a messenger who calls to the worship of Allah the Almighty) before you to any people, the wealthy ones among them said, "We found our fathers following a certain religion, and we will certainly follow in their footsteps." [43:23]

Those who cannot produce any proof for their plea resort to this type of invalid argument. That, of course, is reasonable. How can they be sure that their ancestors were right? Then again, why should they blindly follow their ancestors' footsteps? Allah the Almighty said, "When it is said to them, follow what Allah has revealed, they say, No! We shall follow the way of our fathers. What! Even though their fathers were void of wisdom and guidance?" [5:104] Also, "Even if their fathers knew nothing and were astray?" [2:170] To follow the footsteps of fathers is commendable if they were on the right path. Concerning Joseph (peace be upon him), Allah the Almighty said: "And I follow the ways of my fathers, Abraham, Isaac and Jacob: Never could we attribute any partners whatsoever to Allah; that comes of the grace of Allah to us and to mankind, yet most men are ungrateful." [12:38] Allah also said, "And those who believe and whose families follow them in faith, to them shall We join their families." [52:21]

Suspicion was always raised by people in answer to the call of Prophets. The people replied to the call of Noah (peace be upon him), as we notice in the Holy Quran, "We sent Noah to his people, he said, "O my people worship Allah, you have no other god but Him. Will you not fear Him?" The unbelievers among his people said, "He is no more than a man like yourselves; his wish is to assert his superiority over you. If Allah had wished to send messengers, He could have sent down angels. Never did we hear such a thing as he says among our ancestors of old." [23:23-4]

The unbelievers wanted to take the practice of their ancestors against the commands of Allah which were presented to them by their Prophets (peace be upon them). As Allah the Almighty stated in the Holy Quran: The people of Saleh said, "Do you forbid us to worship of what our fathers worshipped?" [11:62]

The people of Shu`aib said, as Allah pointed out in the Holy Quran: "Does your religion of prayers command you that we leave whatever our forefathers used to worship?" [11:87] The people of Abraham, after they were silenced by argument, said, as stated in the Holy Quran, "...We worship idols and we remain constantly in attendance on them. (Abraham) said, "Do they listen to you when you call on them or they do you good or harm?" They said, "Nay, but we found our fathers doing so."" [26:70-4] Pharaoh said to Moses, as Allah demonstrated in the Holy Quran, "...What then is the condition of previous generations." [20:51]. Who were before you and did the same thing by following the footprints of their parents. Look what happened to them. Thus unbelievers, have been opposing the truth with weak and foolish arguments. From Islaam.com