Son of Benazir Bhutto and Asif Ali Zardari speaks of sacrifices made by family on fifth anniversary of mother's assassination

He stood yards from the tomb of his mother, a two-time prime minister killed by Islamic militants exactly five years before, and that of his grandfather, a prime minister and president ousted in a military coup and hanged by a dictator, and told the huge crowd filling the open ground in front of the white domed mausoleum that there were "two powers" in his homeland, "those on the right path and those on the path of lies".

On Thursday Bilawal Bhutto Zardari, the 24-year-old only son of Benazir Bhutto and the heir to one of the most powerful, famous and controversial political dynasties in the world, made his formal debut in the turbulent and often lethal world of Pakistani politics at an emotional rally in a small village which is his family's ancestral home in the south of the country.

"Bilawal has arrived. This was a huge step. It was make or break for him," said Nadeem F Paracha, a well-known columnist with Dawn newspaper after the speech.

Less than three years ago, Bhutto junior was studying history and politics at Christ Church college, Oxford, a target for tabloid journalists but few others. Now he is probably the most high-profile target in a country hit by wave after wave of extremist violence.

Bhutto spoke of the sacrifices made by members of his family, workers of the Pakistan People's party (PPP), and others such as Shia Muslims shot dead in ongoing sectarian violence and Malala Yusafzai, the 15-year-old schoolgirl and activist for girls' education who was shot and badly injured by militants in October and is now recovering in a British hospital.

"How long you will go on killing innocent people? … if one Malala will be killed, thousands will replace her. One Benazir was killed; thousands have replaced her," Bhutto told the crowds.

Observers noted that Bhutto's Urdu, the national language which he has had to hastily learn since his return to Pakistan to take up his political heritage, was, if still accented, much improved.

"He does not believe in being the anointed prince. He wants to earn the respect of the party workers and of the people of Pakistan," said Farnahaz Ispahani, a former PPP member of parliament and a confidant of the Bhutto family.

More than 5,000 police had been deployed to protect the event. Helicopters hovered overhead.

Parliamentary elections due this spring are likely to test the ruling PPP-led coalition, hit by an ailing economy, rising prices for basic foodstuffs, continuing violence, anger at endemic graft and an ongoing power crisis that brings daily electricity cuts.

Bhutto's father, Asif Ali Zardari, has been the president of Pakistan since 2008. A controversial figure who was jailed on corruption charges that he has said were politically motivated from 1996 to 2000 but who has proved a skilful tactical politician, Zardari has been described as a "transitional leader" for the PPP.

Though only able to contest elections in September after his 25th birthday, Bhutto's presence will nonetheless be a powerful boost in campaigning over the coming months.

"Bilawal grew up with his mother as his father was in jail for a long time. He went with her to rallies and was with her in top-level meetings. His beliefs – in pluralism, democracy, human rights – mirror hers," said Ispahani.

However, doubts remain over Bhutto's appeal to new, younger, urbanised and often more religiously minded voters. Osama Siddique, a professor at Lahore University of Management Science, said it was hard to "visualise Bilawal" in a key position in the immediate future.

"Putting Benazir's son on a stage makes political sense. It's a very poignant and emotional moment still for many people," he said.

Cyril Almeida, analyst and editorialist in the southern city of Karachi, said that though Bhutto's personal courage was unquestionable it was less certain that a political novice could "solve the problems faced by the country … whatever his last name".

Benazir Bhutto died when leaving a political rally in the northern city of Rawalpindi while campaigning for elections in 2007 after nearly 10 years in exile. Her killers have never been conclusively identified, though most experts and intelligence services believe Islamic extremists were responsible. The PPP won the postponed polls held after her assassination to gain power.

Party officials told the Guardian on Thursday that Bilawal, who was educated at private English-medium schools in Pakistan and in Dubai after his mother went into self-imposed exile in 1999, would contest his mother's parliamentary seat when he was old enough.

Last year Fauzia Wahab, a presidential aide and Bhutto family friend, said Bilawal carried "a heavy burden" as he "had the Bhutto genes".

Benazir Bhutto's father, Zulfiqar, rode to power on an anti-poverty platform before being deposed and eventually executed in prison by the military dictator Muhammed Zia-ul-Haq in 1979. Both he and his daughter are routinely referred to as "shaheed" or "martyred" in Pakistan.

Bhutto told the crowd on Thursday that the PPP stood for "food, clothes and shelter" for the common man, purposefully using a slogan from his grandfather's campaigns. Bhutto, who friends say reads history avidly, also appeared well aware of the potential cost of his new role.

"The PPP is not just a political party. This is our life," he said.

Dynastic politics

In an uncertain south Asia, it is always nice to have something you can rely on. In Pakistan it is that a Bhutto will be either in power or leading the opposition. Zulfiqar Ali Bhutto dominated the early 1970s with his brand of populist, leftwing, nationalist and increasingly autocratic politics. His daughter was prime minister twice. Now it's her son's turn to enter the fray.

In India, the great local democracy, the Nehru-Gandhi dynasty is as dominant as it has ever been with Rahul Gandhi, 42, hoping to become a fourth-generation prime minister, or at least principal candidate, and his mother, Sonia, currently the president of the ruling Congress party.

In Bangladesh, the decades-old rivalry between Begum Khaleda Zia and Sheikh Hasina Wajed for control of the country continues that between the late husband of one and the father of the other. Bhutan is still a monarchy.

In Burma, the Nobel-prize-winning democracy campaigner Aung San Suu Kyi, the daughter of the assassinated nationalist leader and effective founder of the modern country Aung San, is leader of the opposition and spoken of as a potential president in the future.

In Sri Lanka, the son of the president, Mahinda Rajapaksa, himself the son of a prominent politician, has won a seat in the family fief of Hambantota and significant numbers of family members fill posts across the country's administration.

At state or provincial level in all these countries, similar dynamics are at work. Why are dynastic politics so tenacious on the subcontinent? In an often mercenary world, there is the obvious need for any successful politician to bolster his or her hold on power by recruiting loyal retainers who will not defect for material gain. This means family first. Then there is simple inheritance of power, influence, money and, especially in India and Pakistan, land. A key factor is the importance of personalities in contests largely stripped of ideological content. Finally there are the high levels of illiteracy, which make a famous name a determining factor for tens of millions of voters.

One common strand uniting the dynasties is that most of them speak English as a first language. Along with railways and a swollen bureaucracy, it may be that British rule bequeathed something else too: a taste for hereditary power and deference. There are one or two exceptions to the rule. The Maldives has all sorts of political woes but dynastic rule is not one of them. Nepal has recently done away with its kings, though it is hardly a model of stability either. As for Afghanistan, a relative replacing the president, Hamid Karzai, as a candidate, possibly a successful one too, in coming polls is far from impossible. After all, in south Asia, politics is a family affair.