‘Your “father’s”?’ I did the air quotes.

‘Yeah, he’s in Thailand.’

‘I thought he didn’t like you. But he lent you his car?’

‘That’s the sort of thing he does. No love, just stuff.’

The Porsche would be the perfect vehicle to lend to someone you did not like. It was seventeen years old (thus using old emissions technology), had appalling fuel economy, little leg room, high wind noise and a non-functioning air-conditioning system. Rosie confirmed my guess that it was unreliable and expensive to maintain.

As we arrived at Natalie’s, I realised I had spent the entire journey listing and elaborating on the deficiencies of the vehicle. I had avoided small talk, but had not briefed Rosie on the DNA collection method.

‘Your task is to occupy her in conversation while I collect DNA.’ This would make best use of our respective skills.

It soon became clear that my back-up plan would be necessary. Natalie did not want to drink: she was abstaining from alcohol while breastfeeding her baby, and it was too late for coffee. These were responsible choices, but we would not be able to swab a cup or glass.

I deployed Plan B.

‘Can I see the baby?’

‘He’s asleep,’ she said, ‘so you’ll have to be quiet.’

I stood up and so did she.

‘Just tell me where to go,’ I said.

‘I’ll come with you.’

The more I insisted that I wanted to see the baby alone, the more she objected. We went to its room and, as she had predicted, it was sleeping. This was very annoying, as I had a number of plans that involved collecting DNA in a totally non-invasive way from the baby, who was, of course, also related to Alan McPhee. Unfortunately I had not factored in the mother’s protective instinct. Every time I found a reason to leave the room, Natalie followed me. It was very awkward.

Finally, Rosie excused herself to go to the bathroom. Even if she had known what to do, she could not have visited the baby, as Natalie had positioned herself so that she could see the bedroom door and was checking frequently.

‘Have you heard about the Genographic Project?’ I asked.

She hadn’t and was not interested. She changed the topic.

‘You seem very interested in babies.’

There was surely an opportunity here if I could find a way to exploit it. ‘I’m interested in their behaviour. Without the corrupting influence of a parent present.’

She looked at me strangely. ‘Do you do any stuff with kids? I mean Scouts, church groups …’

‘No,’ I said. ‘It’s unlikely that I’d be suitable.’

Rosie returned and the baby started crying.

‘Feeding time,’ said Natalie.

‘We should be going,’ said Rosie.

Failure! Social skills had been the problem. With good social skills I could surely have got to the baby.

‘I’m sorry,’ I said as we walked to Phil’s ridiculous vehicle.

‘Don’t be.’ Rosie reached into her handbag and pulled out a wad of hair. ‘I cleaned her hairbrush for her.’

‘We need roots,’ I said. But there was a lot of hair, so it was likely we would find a strand with its root attached.

She reached into her bag again and retrieved a toothbrush. It took me a few moments to realise what this meant.

‘You stole her toothbrush!’

‘There was a spare in the cupboard. It was time for a new one.’

I was shocked at the theft, but we would now almost certainly have a usable sample of DNA. It was difficult not to be impressed by Rosie’s resourcefulness. And if Natalie was not replacing her toothbrush at regular intervals Rosie had done her a favour.

Rosie did not want to analyse the hair or toothbrush immediately. She wanted to collect DNA from the final candidate and test the two samples together. This struck me as illogical. If Natalie’s sample were a match, we would not need to collect further DNA. However, Rosie did not seem to grasp the concept of sequencing tasks to minimise cost and risk.

After the problem with the baby access, we decided to collaborate on the most appropriate approach for Dr Peter Enticott.

‘I’ll tell him I’m thinking about studying medicine,’ she said. Dr Enticott was now in the Medical Faculty at Deakin University.

She would arrange to meet him over coffee, which would provide an opportunity to use the coffee-cup swab procedure that currently had a one hundred per cent failure rate. I thought it unlikely that a barmaid could convince a professor that she had the credentials to study medicine. Rosie seemed insulted by this, and argued that it did not matter in any case. We only had to persuade him to have a drink with us.

A bigger problem was how to present me, as Rosie did not think she could do the job alone. ‘You’re my boyfriend,’ she said. ‘You’ll be financing my studies, so you’re a stakeholder.’ She looked at me hard. ‘You don’t need to overplay it.’

On a Wednesday afternoon, with Gene covering a lecture for me in return for the Asperger’s night, we travelled in Phil’s toy car to Deakin University. I had been there many times before for guest lectures and collaborative research. I even knew some researchers in the Medical Faculty, though not Peter Enticott.

We met him at an outdoor café crowded with medical students back early from the summer break. Rosie was amazing! She spoke intelligently about medicine, and even psychiatry, in which she said she hoped to specialise. She claimed to have an honours degree in behavioural science and postgraduate research experience.